Ultra-violet sensitive photographic element



I element which is stance.

. longer visible Patented Oct. 4, 1932 1 UNITED STATES PAT ENT' OFFICE ROBERT E. BURROUGHS, OF ROCHESTER, NEW YORK, ASSIGNOR TO EASTMAN KODAK COMPANY, OF: ROCHESTER,

NEW YORK, A CORPORATION OF NEW YORK ULTRA-VIOLET SENSITIVE PHOTOGRAPHIG ELEMENT N0 Drawing.

This invention relates to a photographic sensitive to the extreme ultra-violet portion of the 'spectrum.

In modern industrial and scientific research spectra-photography plays a considerablepart, and in this field the characteristics of various materials under the influence of ultra-violet radiations are of interest. Much of this kind of work is now done with the quartz spectrograph and measurements are made from the visible as far into the ultra-violet as is possible. course, all done with the cially obtainable photographic plates or films. The materials available have, however, introduced difliculties due largely to the fact that the gelatin in which thesilver halide grains of the emulsion are embedded absorbs the radiations of very short wave lengths, thereby preventing their action upon help of commerthe silver halide grains which in themselves are sensitive to the radiations.

A number of previous workers have attempted to overcome this drawback by incorporating in the emulsion a fluorescent sub- The purpose of such a substance in general is to transform the radiations of short waves into lengths which are not so strongly absorbed by the gelatin. In this way the invisible short wave lengths are changed into the wave lengths which are able to act upon the silver halide grains, as they are not absorbed by the gelatin These radiations will'usually be of a blue or greenish color.

I have found a material and a method which is particularly satisfactory for sensitizing a photographic plate or film to the extreme ultra-violet. use is ethyl-dihydro-collidine-dicarboxylate. This material is put on the surface of the emulsion in a very thin layer, and is removed bythe-subsequent treatment of the plate or film. Y t

Application filed May 6,

This work is, of

radiations of longer wave- The material which I h 1931. Serial No. 535,576.

.. A satisfactory method of applying this thin coating is to bathe the plate for a few seconds in a solution of ethyl-dihydro-coL lidine-dicarboxylate. A suitable bath is the following: Ethyl-dihydro-collidine-dicarboxylate 5 gm. Ethyl acetate; 95

ment are removed by washing the plate in alcohol or by brushing with a tuft'of cotton during development. The method of sensitizing to the ultraviolet'as described older method of incorporating the fluorescent material in the emulsion, and by the present invention the sensitizer is completely removed without any additional steps and no trace of its presence is left in the emulsion after development and fixing. Plates or film sensitized in the manner described with has advantages over the ethyl dihydro collidine e dicarboxylate will show a sensitivity in p. I What I claim is:

1. A photo-sensitive gelatino silver halide layer comprising ethyl-dihydro-collidine-.

dicarboxylate.

2. A photographic element comprising a support, an emulsion layer containing silver alide, and on the surface of said emulsion layer a thin superficial coating of ethyl-dihydro-collidine-dicarboxylate.

Signed at Rochester, New York, this 28th day of April: 1931.

- ROBERT E. BURROUGHS.

the ultra-violet beyond 

